function plotLink_P(j)
global uLINK
%possion = zeros(3,2);
for n=1:j
    robotlink = uLINK(n).p;
    possion(1,n) = robotlink(1,1);
    possion(2,n) = robotlink(2,1);
    possion(3,n) = robotlink(3,1);
end
    plot3(...
        [possion(1,1),possion(1,2)],[possion(2,1),possion(2,2)],[possion(3,1),possion(3,2)],...
        [possion(1,2),possion(1,3)],[possion(2,2),possion(2,3)],[possion(3,2),possion(3,3)],...
        [possion(1,3),possion(1,4)],[possion(2,3),possion(2,4)],[possion(3,3),possion(3,4)]);
        xlabel('x'),ylabel('y'),zlabel('z');grid on;axis equal;

end